SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae7f5ec03c95f1d19a817d528b068a53000bf30e0232a20399e44cc755ccef2e' 
  AND token = 'euUn2ajfm90bPLOOkDcDpljdIsFeNpr0JDdNyfY/bsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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