SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8993d20a107db0586f847411252147df80ac9b946ca06255d7ce47b22a61693' 
  AND token = 'KoL3IcazK6/GRlNkhj/DqR09GP+c/SoV6ZkzCdSTDSQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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