SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66612e44dba79dbae17f669ce931cd26c9b133a9846bbebcc96e010cb61de963' 
  AND token = '6uYUYu3uWRXVzymxFdZ2ug26QpCGcZETxRK5fwdApQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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