SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd517a5a25c588fb1b116a4121076bada83eff58cb081c45aef619c5e75b08dc5' 
  AND token = 'BiwQU+JNvorjzRG6jogzmY1AA04LMKlws7AeCI0uVI4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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