SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af4346d58adc950273ed18a5fefaee0881e27062865db5a52eee7fb767332935' 
  AND token = 'XXl1QYAeS/7BdzsobHVhWV45hyVYqomQGazkWyNmQTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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