SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff8087041d21c5226395b1c87eee516b2ce9e603530d1a1369f8ae482b766470' 
  AND token = 'aNe2Q8i2ocuOwEu6olf1UtVqUU/2Km2zWftHGrDQRN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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