SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2857c56119664d586176b7583b089b16b767d4dbd97b5f0d9a44043bed9881f' 
  AND token = 'rOBp4zmJm0zXT4XJSYp2zjWcLVrydRzK1sZHgAhsF8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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