SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e670c07dec99f11f5100b62555112d0cd8ad4960770dbaa43e2f25bfaa93af36' 
  AND token = 'QKJdDIpf2vXwlhlnt3gfmYtSwtl9qV4/jaOjV3DLk44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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