SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14c152cc277888b30a8fd1dfa1ee22392d5090568b9419b109dd5ff22992b979' 
  AND token = 'KYVa6zPWLk3lhAhXck855XqokB87UPKYKvBe5oYdfOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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