SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb42421165081f414f271a2c18e9c922a2751cfe15aabb66a8d42202293b2521' 
  AND token = 'y1zTMX1AUi25nqDWDqjAQFWSjSxR+g3PGYmUxTmBDII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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