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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6dd97a61aa880607e59bb154548597dee6ff1e7b1e3e97f7163f1267940aa3e' 
  AND token = 'f4Tjvtij03jJBDyUqSV8m+GCJTNXvH96DHW/A4fAr7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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