SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3cbe7a967dd5b3e833d87a73cca6db89967e65547749e28006d556daf8a9d6c' 
  AND token = 'vDzwONrLOakXBexrH+cIcftVVBPHqEKTtZXBxm4MXo8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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