SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b27c9f1019c504e1b9925085dc5cb84731d8501ddfa9f37217168fbdbd0ce2d9' 
  AND token = 'RIp1BVnvaKGHNvnVUHsApsc+eW4+0e19DQyA+2WzDKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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