SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df14d960f1de699e2e5b538bb7d2401215fabf11e84a257101ec74a00712f6da' 
  AND token = 'nZEbpScTF+KZHoZawseKkApllChNAmvCrRuFacaATFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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