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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a09f9e2ca3fcb53d80bda5dc002db4b16601a381bf7a66413e7e14e277b5ce21' 
  AND token = 'NFcMfQ7Ni1DCdTZh5yikfr9EAgTDxeEJ1wf3RH76Img=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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