SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fca666ad3dfdbebd308de869466aeecd1d0b8d1676ded92ebeaa1b75aeddb3d' 
  AND token = 'rG12m+Moag4rpbeG4Xgvee2wYkR7wABJBvSAK24N20Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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