SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b3e4d8ffc266e2be678a489f3ebab6cf670753942dc712a6b6ee7a4e8e1e5ed' 
  AND token = '/sPuxFz+Sf0e2OTslzqvQImZVTrnnFwRxqshDmgXgiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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