SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f82559df2288dac4add416c98a7709b6be701e1c2479e48e49cb4610aae916a' 
  AND token = 'QYjUHe2uDNATBdsEn0HdqfHIvMePMG+5u+kHs11ftd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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