SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8e89aa2d9a750035e52d6ff9981657b47acf64af09add812ae60493882638141' 
  AND token = 'jMebuGTeatSRvtu3K926sMuWyy+/oXll97iEYJyzNL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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