SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f8678ee80157736747b369023f704ca9dc01a3a1fa191fcc9c6b28e902df76a' 
  AND token = 'cqtORPPr32L8sitaWJ5fbfBdA3ZwYDPljsVSKbPGnnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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