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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39e2c3001ef6a906623139a798c20fd5d40febe7ee37db34b5b11162b6c8ae51' 
  AND token = '5YVLv2zgMsL+lDg6cMR1EomQEHFhT3TdAGlCZoON+vI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}