SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd27cef358062ce0e0b801c03101064a657805a8097a31b77b247418ef70201d7' 
  AND token = 'DoF20cMdXixetiqDiksz79gDm5MixM8BYREdM/i6AXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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