SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c48c8b2897572f288ffacd0963901f70de19ac0b5cf8b309c0159a79da8d7ddb' 
  AND token = 'sxlnV8p2q/Qi6OPIG1KL0e5TTCYojcs0lmoimmSj+Hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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