SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '901e6e15f94a45450993608bade49d46ee457095169b0aebb535d5343f248241' 
  AND token = 'X9ium1WKyMzo9uHm2pjj26pI+UvVWrlJOvmgkTwhQ6s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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