SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7966761d3b8dca28406194e8662125656bc5db46019adc8017b21698c38fabc4' 
  AND token = '/1usQ8+DwGQdO2QpOxjAuHDDJxNouFRqY3fHRXzRcA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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