SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c1defc92c30b2ba5471c8a4be6d0d785f2e7f63b7282dd93c2001730c6c4969' 
  AND token = 'SimZjwBJjz6EvjU4+bjyRZ/KDbjB/Qut4jp/Dw2W+bM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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