SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27c2650978b4627a635abd6f9b9e3a0f2476428b91d93f10fac0cfd615d20af0' 
  AND token = '4JlYnlSK7Gkvdv38xu4y+R2E5MFR+3hMNhZssGE/Pnc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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