SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b610a8112efb7f6b8cbb4abafcf7e2cee952f087e77d71ff70285c99852fd275' 
  AND token = '5So54Zfx9fJypdy+eSrOgXyiDIVyUD8xFHkIM3EmoiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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