SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '281d78362cc0d16cbe75b7f50bcfa61025c648558c4a7271f6c4f9096ec4bd3c' 
  AND token = 'TRWmPGszRrkVQgwLyQtK6AFE1YMPcZ4gG1hrKezE9yA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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