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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6d0d5ee3af7beb51fd5d6e4837cd42583311398e864cca359639ce6b563df02' 
  AND token = 'ROYCsrDhXf/R4OqhjZWS9xUQ9vaX+7gRMDyPiD1xOWE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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