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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ac46b03cf7967a825fc7b6490c2efa10de191acf8ef8ee85172e7e1a3bbab00' 
  AND token = 'dCLlBQ+jm3i7yFQqrQj1jA6d9ccFj/rYhZ04p0Otmxg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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