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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3f83a6aa994e0b2e08ee200b78c1a36cd73adfd399b54c6efadac5c78f94cf3' 
  AND token = 'p6PkMOvkPAgQXQFBwP1UaGHIVMjdH5L6QZXdRH1v9DI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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