SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7498d0b4395affd6b0d246e9454915d853989eb03aa342cde2cefbe752d1770' 
  AND token = 'wccPaM7+0nSSED1+ZztaW1321CXmas8AFTRnsasEu9Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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