SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc54ce2c30a410e0408c86b8a84da30961b5104942659de142d0ce3e5e2a1686' 
  AND token = 'z3shvoHYNspJVWnuYWMleDvolm+JD7dApqp8SlXTcxQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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