SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '188f6a62f756c174848c50a6da35f4dd36ce5dd96f279d27d73828b5cdb63016' 
  AND token = 'ZW1vslMphlzi6GWq3E/WGAmN12WF/nHa937KWkRijLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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