SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7681ef09d3524ed7ccf21f356ba130735a99c1f08b05523c1865ffadd6c8a3ec' 
  AND token = 'eBM3xY0HA2VPzJl4AsUtBjOBZBhnOZAVgz85npFk46g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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