SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3090a4b1994837a8a0eac1f93c34c850c9da7c10e00542016ab2eb6ebc59d5b' 
  AND token = 'CBqT12+9ep++6lHXdfBcz95sL2uzgwUFGDEEhTp/7xA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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