SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0a9a8dc314cbe3f52d4bd7a92c5d57901ca049c24c9f302ea00eb38202f7396' 
  AND token = 'd/KpfbFxRWnGLIOzYN+rWykgqcIXvwvQWArqKJNnYE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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