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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad21ca31a57ecf4ac7ce0aad121a73c8419f6109714fa20b316af7de11571aa1' 
  AND token = 'Q0T4fpTC5dVCjtzOvYWfAcqbuXNsrSI83TkYqGXxDes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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