SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e15dcd659a5fd150b8936ea4b4a5c36c56aadcf7a0aba0592f10e47cfb9c34d2' 
  AND token = 'u0qkwMAdZwly1+f2+LG5LUBT99CyUesauPaFxv3wZGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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