SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8abf5326a3bb1edd410a1b8627fb839758b1d28609d6fff36b10978e32f56c7' 
  AND token = 'RY7QdhTXfQpKPlxD9ZMEPjGpuKQyGHktXMEwYwBf3Ok=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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