SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '494f14e997f23cf7879c993d5134d2bbd459cdbb373f7bd233d946e4f92d6cd6' 
  AND token = 'nTHrV9gMbOiAae53V2+BePv1zmV3rDnHng0G+6x12bs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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