SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8393c2179db2efd75ee0136ab637ac32a3e5c0c59cbaf6865bbd8ec5c488c5e' 
  AND token = 'iI2cmB2oB2wR9nEwPHnm6/lVhpVOpR3IFYNvNlXpcjo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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