SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '330a0b3ebec572d0bddcb69765d44c25e4182a57d96342a2d94bcce8b2ccda1c' 
  AND token = '9nk/koXs87KbCrINieq900v6e8pBGPXGgeuBPHGspR8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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