SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83c5cb8888e3888d3828a8cfceffb060a64aaccef0d368caed5ccba81285003e' 
  AND token = 'qR8H9Ryx2+GOZ43LtzcHM6A+X4Cpsm8NKzWxobEKYBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00078

JSON explain

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