SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a268b19f1a5d408f43f5735e9cec3972c4fbd20b13f22b43459097a479bc2a1a' 
  AND token = 'G8eYp4XTMopaffINxu4eX0sNoI/flabkQHwuJydkOAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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