SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e82d8ccc5426fbec4d64074ab56fde78d13e5e844b557bcdb4d950c6301ffd4' 
  AND token = '6dMTB9au9mbjzdRFyvP2EGxzoBfk1Lg2MB0AlZT+Fus=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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