SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dbba1f7550a32049225fe2cf64031fc670aeafa6840ecec1952b1a6f6e48155' 
  AND token = '3KBPK0xnx8fO81ggIspxUGqpSCRuFAZCMK/XYe1xDvA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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