SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0891ad10a7d3a6753b8816880c2bfb1a526994c02594417c1854dc260685785e' 
  AND token = 'PzEOphzg9UYQk5YEwkmcsdvMHGslR3RFUECitXvbvYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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