SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78f66fa4868ba68fa33d4ac7ef80ed8764d572808efce8a17e8e748266c55b62' 
  AND token = 'V7iJlUBi9PkWXIrRfn+MZ4mVM6ca+rETJk2Z61q8Vxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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