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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8c9db09a4f76cbdf19d74bcdb907e4f8b638267d9883bca85aaa9e0ac39fa4a' 
  AND token = 'S3yNGGGPjiPtdCrGVZkE1xXMUDT2fubmw/cxykEgZvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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