SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90d8a72656e3779a282d8697e100a52c70fb57a3a0c530fa6bfce1693ce2335a' 
  AND token = 'URWIzUVP+jFetxiRa58EAKtJPUo+QUGQc+uEx4aZReE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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