SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a38b7e0552183087a874822b4b65459acf2f815161586363247e259462d7cfed' 
  AND token = 'C6gzK1rqG9AhPXzMeQ2dbXPGvdRsaxALr0F0AXFUORc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}