SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81367fe0f89997db336a2549081bf719072f49256879b76f0f8611379ee8caed' 
  AND token = '96wj0rJNY2ypBVPBiGkz8AfSUsBb9dg5/wXYaWdKmVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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