SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81f5fb33c24bde5ae549d6c9bbce4e9b48cdd72bb1ed019e319feaeba2bfd7f5' 
  AND token = '1onR6AGTiT8WH/O1Kyf5Q3iomyEEAr53h19DBB/CIMo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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