SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '0350f5d317ef2c8b81c87015eb07cffc544ba4f15bb3d7895f6e1997fbef6451' 
  AND token = '/DQrpNFQfLFOxWaUZKtjsz0vLnHuYKBEg4w7rGLDH4k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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