SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97e74232a9857f3be83389b09babe4fd5f8b15471b4c28738349449f217a3ced' 
  AND token = 'NUcdqVMjhPZHh65+njFt1ZlHL8RHIKPmrtiXBw7epVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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