SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3f27b33d78790bc4738827a9a19a939161d7eebde946e2c7031bd9e0a3000de' 
  AND token = 'UNdoDHXKlojOF/Xg5aOppJvnxzy5EIuGngXsOhS0KQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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